A conventional master clutch functions as a releasable coupling between an engine and transmission components in a motor vehicle. Such clutches include a driving disc attached to an output shaft on the engine, and a driven disc attached to an input shaft on the transmission. To engage the clutch, the driving disc and the driven disc are forced into contact with each other, thereby reducing the relative speed difference between the discs until they are coupled through frictional force.
When the transmission is in neutral and the clutch is disengaged after being engaged with the engine running, the inertia of the driven components tends to keep them rotating, with only a gradual decrease in speed due to friction. This residual rotation prolongs the time required to complete a gear shift in the transmission because the driven components must slow down to the correct speed to allow engagement of the next gear. Therefore, after the clutch is fully disengaged, it is desirable to reduce the time required for the driven components to slow down, in the case of a moving upshift, or to stop rotating completely, in the case of a stationary shift.
It is well known in the art to retard rotation of the input shaft by using a clutch brake, which is activated by a clutch release bearing assembly upon sufficient disengagement of the clutch. Such a clutch brake typically has a steel core with friction material on each side of the core. After the friction material is sufficiently worn, however, the steel core causes damage to the clutch release bearing assembly and other surrounding components upon sufficient disengagement of the clutch.